ES2948811T3 - Procedure for the manufacture of a (co)polyester - Google Patents

Abstract

The present invention relates to a method for preparing a (co)polyester in a degassing installation, in which the (co)polyester consists at least partially of 1,4-butylenedicarboxylate units, characterized in that the raw (co)polyester It is degassed at a pressure of between 5 and 300 mbar in the presence of 0.1 to 5% by weight, with respect to the total weight of the ingredients, of an entraining agent. (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

Procedure for the manufacture of a (co)polyester

The present invention relates to a process for the manufacture of a (co)polyester, wherein the (co)polyester consists at least partially of 1,4-butylenedicarboxylate units, in a degassing unit, characterized in that the (co) Raw polyester is degassed in the presence of 0.1 to 5% by weight, based on the total weight of the input materials, of an entraining agent, preferably continuously for an average residence time of 0.1 to 2 minutes, and at a pressure between 5 to 300 mbar.

In particular, the present invention relates to a process for the manufacture of a polymer mixture containing one or more (co)polyester(s), which are constituted at least partially by 1,4-butylenedicarboxylate units, in a unit degassing, which simultaneously acts as a mixing unit, characterized in that the raw (co)polyester is mixed, if appropriate, with other auxiliary substances and polymers, and degassed in the presence of 0.1 to 5% by weight, based on the weight total of the polymer mixture, of an entraining agent - preferably water - preferably continuously for an average residence time of 0.1 to 2 minutes and a pressure between 0.1 to 300 mbar - preferably 5 to 100 mbar .

From the literature, procedures are known for the continuous manufacture of polyesters such as polybutylenesuccinate (PBS), polybutylenesuccinate-coadipate (PBSA) or polybutylenesuccinate-cosebacate (PBSSe) (see documents WO-A 2009/127556 and EP-A 2228399). These documents describe the decrease in the concentration of tetrahydrofuran formed. The procedures described in these writings however do not lead to a sufficient decrease in the concentration of THF, to obtain an approval for contact with food according to EU 10/2011.

Document WO 2017/148931 describes a procedure for reducing the concentration of THF in polymer mixtures containing one or more (co)polyester(s), which are constituted at least partially by 1,4-butylenedicarboxylate units. . To do this, the mixture formed of polymers is left for several days at high pressures and temperatures in a stream of air. With regard to space/time performance and energy efficiency, this procedure cannot be completely convincing.

Therefore, it was the objective of the present invention to provide an efficient and applicable procedure for the manufacture of (co)polyesters with a low concentration of THF or a mixture of polymers containing one or more (co)polyester(s), where The (co)polyester consists at least partially of 1,4-butylenedicarboxylate units, which does not exhibit the disadvantages described above.

Surprisingly, a process was found where a crude (co)polyester is degassed in the presence of 0.1 to 5% by weight, based on the total weight of the crude (co)polyester, of an entrainer in a unit of degassing, at a pressure between 5 to 300 mbar.

This process is essentially more efficient than a corresponding process at the same pressure, although in the absence of an entraining agent, such as preferably water.

An interesting variant is the procedure for the manufacture of a polymer mixture containing one or several (co)polyester(s), which are at least partially constituted by 1,4-butylenedicarboxylate units, in a degassing unit, which simultaneously acts as a mixing unit, characterized in that the raw (co)polyester is mixed, if appropriate, with other polymers and auxiliary substances, and degassed in the presence of 0.1 to 5% by weight, referred to the total weight of the mixture of polymers, of an entraining agent - preferably water - at a pressure between 0.1 to 300 mbar - preferably 5 to 100 mbar.

The invention is described in more detail below.

(co)polyesters are understood as i) aliphatic polyesters and copolyesters, ii) aliphatic aromatic copolyesters and iii) aromatic polyesters, which in each case are made up at least partially of 1,4-butylenedicarboxylate units. Particularly preferred are biologically degradable aliphatic and aliphatic-aromatic (co)polyesters according to DIN EN 13432.

Aliphatic (co)polyesters i) are understood to mean those polyesters and copolyesters, which are predominantly constituted by aliphatic monomeric dicarboxylic acids and 1,4-butanediol.

Suitable aliphatic dicarboxylic acids or their ester-forming derivatives are generally those with 2 to 40 carbon atoms, preferably 4 to 14 carbon atoms. Preferably they can be linear and also branched. The cycloaliphatic dicarboxylic acids usable in the context of the present invention are generally those with 7 to 10 carbon atoms and in particular those with 8 carbon atoms. However, in principle dicarboxylic acids with a higher number of carbon atoms, for example with up to 30 carbon atoms, can also be used.

By way of example, mention is made of: malonic acid, succinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brazilic acid. , tetradecanedioic acid, fumaric acid, 2,2-dimethylglutaric acid, suberic acid, fatty acid dimers (such as Empol ^® 1061 from BASF SE), 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, acid 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid, maleic anhydride and 2,5-norbornanedicarboxylic acid.

As ester-forming derivatives of the aforementioned aliphatic or cycloaliphatic dicarboxylic acids, which are also usable, mention is made in particular of di-C ¹ to C ⁶ alkyl esters, such as dimethyl-, diethyl-, di-n-propyl, diisopropyl , di-n-butyl, di-iso-butyl, di-t-butyl, di-n-pentyl-, di-iso-pentyl or di-n-hexyl ester. Likewise, the anhydrides of dicarboxylic acids can be used.

In this regard, dicarboxylic acids or their derivatives that form esters can be used, individually or as a mixture of two or more of them.

Preferably, succinic acid, adipic acid, azelaic acid, sebacic acid, brasilic acid or their respective ester-forming derivatives or mixtures thereof are used. Particularly preferably, succinic acid, adipic acid or sebacic acid or their respective ester-forming derivatives, or mixtures thereof, are used. Particularly preferably, succinic acid or a mixture of succinic acid with preferably 25 mol% of adipic acid or preferably 10 mol% of sebacic acid or its ester derivatives, such as its alkyl esters, is used.

Succinic acid, azelaic acid, sebacic acid and brasilic acid also have the advantage that they are accessible as renewable raw materials.

In general, 1,4-butanediol is used as the aliphatic diol.

Aliphatic (co)polyesters containing the following components are preferred:

i-a) 80 to 100 molar %, referring to components i-a to i-b, of succinic acid;

i-b) 0 to 20 mol%, referring to components i-a to i-b, of one or more dicarboxylic acids chosen from: adipic acid, azelaic acid, sebacic acid or brazilic acid;

i-c) 99 to 100 mol%, referring to components i-a to i-b, of 1,4-butanediol;

i-d) 0 to 1% by weight, based on components i-a to i-c, of a chain elongating agent and/or branching agent.

As a general rule, polyesters i-a to i-d contain 0 to 2% by weight, preferably 0.05 to 1.0% by weight and particularly preferably 0.1 to 0.3% by weight, based on the total weight of the polyester i, of a branching agent and/or 0.1 to 1.0% by weight, based on the total weight of the polyester i, of a chain elongation agent. The branching agent is preferably an at least trifunctional alcohol or an at least trifunctional carboxylic acid. Suitable chain extension agents are in particular isocyanates, difunctional isocyanurates, oxazolines, carboxylic acid anhydrides or epoxides.

Particularly preferred branching agents have three to six functional groups. By way of example, they are mentioned: tartaric acid, citric acid, malic acid; trimethylolpropane, trimethylolethane; pentaerythritol; polyetertriols and glycerin, trimesic acid, trimellitic acid, trimellitic anhydride, pyromellitic acid and pyromellitic dianhydride. Polyols such as trimethylolpropane, pentaerythritol and in particular glycerin are preferred. Using the component, biologically degradable polyesters are built, with a structural viscosity. Biologically degradable polyesters are more easily processed.

Within the scope of the present invention, a diisocyanate as a chain extension agent is understood to mean, in particular, linear or branched alkylene diisocyanates or cycloalkylene diisocyanates with 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example 1,6 -hexamethylene-diisocyanate, isophorone diisocyanate or methylenebis(4-isocyanatocyclohexane). Particularly preferred aliphatic diisocyanates are isophorone diisocyanate and in particular 1,6-hexamethylene diisocyanate.

By polyfunctional epoxides as chain elongation agents, we mean in particular a copolymer having epoxide groups, based on styrene, acrylic acid esters and/or methacrylic acid esters. The units bearing epoxide groups are preferably glycidyl(meth)acrylates. Copolymers with a proportion of glycidyl methacrylate greater than 20, particularly preferably greater than 30 and particularly preferably greater than 50% by weight of the copolymer have proven to be advantageous. The epoxide equivalent weight (EEW) in these polymers is preferably 150 to 3000 and particularly preferably 200 to 500 g/equivalent. The average molecular weight M ^w (weight average) of the polymers is preferably 2000 to 25,000, in particular 3000 to 8,000. The average molecular weight M ⁿ (arithmetic average) of the polymers is preferably 400 to 6,000, in particular 1000 to 4,000. The polydispersity (Q) is generally between 1.5 and 5. Copolymers having epoxy groups of the type mentioned Previously they were distributed, for example, by the company BASF Resins BV under the brand name Joncryl® ADR. Joncryl®ADR 4468 is particularly suitable as a chain elongation agent.

As a general rule, it is reasonable to add compounds (at least trifunctional) that generate branching at a time prior to polymerization.

Apart from dicarboxylic acids and diols, aliphatic (co)polyesters may contain other of the following components chosen from the group consisting of: dihydroxyl compounds and hydroxycarboxylic acids.

For the manufacture of polyesters, a hydroxycarboxylic acid can be used, such as: glycolic acid, D, -L, -D,L lactic acid, 6-hydroxyhexanoic acid, its cyclic derivatives such as glycolide (1,4-dioxan-2,5- dione), D-, L-dilactide (3,6-dimethyl-1,4-dioxane-2,5-dione), p-hydroxybenzoic acid as well as its oligomers and polymers such as 3-polyhydroxybutyric acid, polyhydroxyvalerianic acid, polylactide ( obtainable, for example, as Ingeo® (NatureWorks company) or as Luminy® (Total Corbion company)), for the manufacture of aliphatic polyesters, low molecular weight and cyclic derivatives thereof are particularly preferred.

The hydroxycarboxylic acids can be used, for example, in amounts of 0.01 to 50, preferably 0.1 to 15% by weight, based on the amount of the monomers.

Aliphatic (co)polyesters are meant in particular polybutylene succinate (PBS), polybutylene adipate (PBA), polybutylene succinate coadipate (PBSA), polybutylene succinate coadipate (PBSSe), polybutylene bacate (PBSe) or the corresponding polyesteramides or polyesterurethanes. Aliphatic polyesters are marketed, for example, by the companies Showa Highpolymers under the name Bionolle and Mitsubishi under the names GS-Pla or BioPBS. New developments are described in WO 2010/034711.

The (co)polyesters i generally exhibit an arithmetic average molecular weight (Mn) in the range of 5000 to 100000, in particular in the range of 10000 to 75000 g/mol, preferably in the range of 15000 to 40000 g/mol. mol, a weight average molecular weight (Mw) of 30000 to 300000, preferably 60000 to 200000 g/mol and a Mw/Mn ratio of 1 to 6, preferably 2 to 4. The viscosity index according to ISO 1628-5 (measured in phenol/o-dichlorobenzene solution (1:1) at 0.05 g/ml) is between 30 and 450, preferably 100 to 400 ml/g (measured in o-dichlorobenzene/phenol (weight ratio 50 /50).The melting point is in the range of 85 to 130, preferably in the range of 95 to 120 ° C.

The MVR (melt volumetric rate) according to EN ISO 1133 (190 °C, weight 2.16 kg) is generally, before chain elongation, in 0.1 to 150, preferably in 2 to 150 cm3 /10 minutes.

The acid numbers according to DIN EN 12634 are generally 0.01 to 3 mg KOH/g, preferably 0.1 to 1.0 mg KOH/g and particularly preferably 0.1 to 0.7 mg KOH/g.

Aliphatic-aromatic copolyesters II are understood to mean linear, chain-extended and, where appropriate, branched, chain-extended copolyesters, as described, for example, in document WO 96/15173 to 15176 or in document ^WO 98/ 12242, to which express reference is made. Likewise, mixtures of different partially aromatic polyesters come into consideration. Recent interesting developments are based on renewable raw materials (see WO2010/034689). In particular, polyesters ii products, ecoflex® (BASF SE), are understood.

Among the preferred copolyesters ii are copolyesters, which as essential components contain:

ii-a) 30 to 70 mol%, preferably 40 to 60 and particularly preferably 50 to 60 mol%, based on components ii-a) to ii-b), of an aliphatic dicarboxylic acid or mixtures thereof, preferably, These are mentioned below: adipic acid, azelaic acid, sebacic acid and brazilic acid,

ii-b) 30 to 70 mol%, preferably 40 to 60 and particularly preferably 40 to 50 mol%, based on components ii-a) and ii-b), of an aromatic dicarboxylic acid or mixtures thereof, preferably as are mentioned below: terephthalic acid or 2,5-furanedicarboxylic acid,

ii-c) 99 to 100 mol%, referring to components ii-a) to ii-b), of 1,4-butanediol; and

ii-d) 0 to 2% by weight, preferably 0.1 to 1% by weight, based on components ii-a) to ii-c), of a chain elongating agent, in particular of a di-isocyanate or polyfunctional, preferably hexamethylene diisocyanate and optionally 0.01 to 0.3% by weight of a branching agent, preferably: trimethylolpropane, pentaerythritol and in particular glycerin.

As aliphatic diacids ii-a, those described above under aliphatic (co)polyesters i can be used. In this regard, dicarboxylic acids or their derivatives that form esters can be used, individually or as mixtures of two or more of them.

Preferably, adipic acid, azelaic acid, sebacic acid, brasilic acid or their respective derivatives that form esters, or mixtures thereof, are used. Particularly preferably, adipic acid or sebacic acid or their respective ester-forming derivatives, or mixtures thereof, are used.

The aromatic dicarboxylic acids or their derivatives that form esters ii-b can be used individually or as mixtures of two or more of them. Particularly preferably, terephthalic acid or 2,5-furanedicarboxylic acid or their ester-forming derivatives are used.

1,4-Butanediol is used as diol ii-c, which is also accessible as a renewable raw material. Mixtures with other diols can also be used.

As a general rule, 0 to 1% by weight, preferably 0.1 to 1.0% by weight and particularly preferably 0.1 to 0.3% by weight, based on the total weight of the polyester, of a branching agent are used. and/or 0.05 to 1% by weight, preferably 0.1 to 1.0% by weight, based on the total weight of the copolyester, of a chain elongation agent (ii-d). Preferred are the branching agents and chain elongation agents (ii-d) which are the same as the branching agents and chain elongation agents (i-d) previously described in detail.

The polyesters ii generally exhibit an arithmetic average molecular weight (Mn) in the range of 5000 to 100000, in particular in the range of 10000 to 75000 g/mol, preferably in the range of 15000 to 38000 g/mol, a weight average molecular weight (Mw) of 30000 to 300000, preferably 60000 to 200000 g/mol and a Mw/Mn ratio of 1 to 6, preferably 2 to 4. The viscosity index is between 50 and 450, preferably 80 to 250 g/ml (measured in o-dichlorobenzene/phenol (50/50 weight ratio). The melting point is in the range of 85 to 150, preferably in the range of 95 to 140 °C.

The MVR (melt volumetric rate) according to EN ISO 1133-1 DE (190 °C, weight 2.16 kg) is generally 1 to 50, preferably 1.5 to 25 cm3/10 min. The acid numbers according to DIN EN 12634 are generally 0.01 to 1.2 mg KOH/g, preferably 0.01 to 1.0 mg KOH/g and particularly preferably 0.01 to 0 .7 mg KOH/g.

As aromatic polyester III based on terephthalic acid, polybutylene terephthalate (PBT) obtained on the market is particularly suitable.

An aromatic polyester III based on 2,5-furanedicarboxylic acid is for example: polybutylene-2,5-furanedicarboxylate (PBF), which can be manufactured as described in documents WO2013/062408, WO2010/077133, WO2007/052847.

The low THF (co)polyesters described above can be used in polymer blends which, apart from the (co)polyesters, contain still other polymers, auxiliaries and additives. This is particularly interesting for polymer blends, which find use as food packaging materials, such as, for example, coffee capsules, food films, snap closure films, food service instruments, drinking straws, drinking glasses. paper or foamed or injection molded skins coated with the polymer mixture, for sausages, cheese and/or meat or as toys.

In a preferred embodiment of the process according to the invention, the decrease in the THF concentration occurs at the stage of formation of the composite material, during the manufacture of the polymer mixture. In this variant of the procedure, (co)polyesters can also be used, which previously had no decrease in the THF concentration.

Preferred polyester blends contain:

i) 5 to 95% by weight, preferably 20 to 80% by weight, based in each case on the polyester blend, of one or more of the aliphatic and aliphatic-aromatic (co)polyesters described above,

ii) 95 to 5% by weight, preferably 80 to 20% by weight, referring in each case to the polyester mixture, of at least one or more components chosen from the group consisting of: polycaprolactone, starches, thermoplasticized starches, cellulose, polyhydroxyalkanoate, polyglycolic acid and polylactic acid.

iii) 0 to 40% by weight, preferably 10 to 30% by weight, based in each case on the polyester mixture, of at least one or more filling materials chosen from the group consisting of talc, calcium carbonate, kaolin, mineral fibers.

Polylactic acid is preferably used with the following property profile:

• a melt volumetric rate (MVR) according to EN ISO 1133 (190 °C, weight 2.16 kg) of 0.5 to 50 in particular 2 to 40 cm3/10min)

• a melting point of less than 240 °C;

• a glassy point (Tg) greater than 55 °C

• water content less than 1000 ppm

• a residual content of monomers (lactide) less than 0.3%.

• a molecular weight greater than 80,000 Dalton.

Preferred polylactic acids are for example Ingeo ^® 8052D, 6201D, 6202D, 6251D, and in particular Ingeo ^® 4020D, 4032D 4043D or 3251D (polylactic acid from the company NatureWorks) or Luminy LX175, Luminy L105 (polylactic acid from the company Total Corbion)

Polyhydroxyalkanoates are understood primarily as poly-4-hydroxybutyrates and poly-3-hydroxybutyrates and copolyesters of the aforementioned poly-hydroxybutyrates with 3-hydroxyvalerate, 3-hydroxyhexanoate and/or 3-hydroxyoctanoate. Poly-3-hydroxybutyrates are distributed, for example, by the company PHB Industrial under the brand name Biocycle ^® and by the company Tianan under the name Enmat ^® . Poly-3-hydroxybutyrates-co-4-hydroxybutyrates from the company Metabolix are known in particular. They are distributed under the trade name Mirel ^® . Poly-3-hydroxybutyrates-co-3-hydroxyhexanoates are known from the company P&G or Kaneka. The poly-3-hydroxybutyrates-co-3-hydroxyhexanoates generally have a proportion of 3-hydroxyhexanoate of 1 to 20 and preferably 3 to 15 mol%, based on the polyhydroxyalkanoate. The polyhydroxyalkanoates generally have a molecular weight Mw of 100,000 to 1,000,000 and preferably 300,000 to 600,000.

Starches are also understood as amylose; thermoplasticized means thermoplasticized with plasticizers such as glycerin, sorbitol or water (see EP-A 539 541, and P-A 575 349, EP-A 652 910) or also with surface modification (see EP-A 937120, EP -A 947559, EP-A 965615). The polymer mixtures according to the invention, which contain from 10 to 35% by weight, based on the total weight of the polymer mixture, of thermoplastic or non-thermoplastic starches, exhibit both a good degradation capacity in the soil, as well as good mechanical properties, such as in particular a high resistance to tear propagation. These starch-containing mixtures are therefore an interesting alternative to those mentioned above that have fillers (containing calcium and/or talc), possibly also in combination with polymer mixtures that have fillers.

Furthermore, the polyesters or polyester blends according to the invention may contain other additives known to those skilled in the art. For example, common additives in plastics technology, such as stabilizers; core forming agents; lubricants and separating agents such as stearates (in particular calcium stearate); plasticizers (plasticizers) such as, for example, citric acid esters (in particular acetyltributylcitrate), glyceric acid esters such as triacetylglycerin or ethylene glycol derivatives, surfactants such as polysorbates, palmitates or laurates; waxes such as erucamide, stearamide or behenamide, beeswax or beeswax esters; antistatic, UV-absorbing substances; UV stabilizers; anti-fog agents or colorants.

The additives are used in concentrations of 0 to 2% by weight, in particular 0.1 to 2% by weight, based on the polyester or polyester mixture according to the invention. The plasticizers may be present in 0.1 to 10% by weight, based on the polyester or polyester blend according to the invention.

It can also be added to polymer mixtures, in particular to mixtures having polylactic acid, 0 to 1% by weight, preferably 0.01 to 0.8% by weight, particularly preferably 0.05 to 0.5% by weight, referred to the total weight of components ia vi, of a copolymer having epoxy groups based on styrene, acrylic acid esters and/or methacrylic acid esters. The units bearing epoxide groups are preferably glycidyl(meth)acrylate. Copolymers with a proportion of glycidylmethacrylate greater than 20, particularly preferably greater than 30 and particularly preferably greater than 50% by weight of the copolymer have proven to be advantageous. The epoxide equivalent weight ( ^e E ^w ) in these polymers is preferably 150 to 3000 and particularly preferably 200 to 500 g/equivalent. The average molecular weight (weight average) M ^w of the polymers is preferably 2000 to 25,000, in particular 3000 to 8,000. The average molecular weight (arithmetic average) M ⁿ of the polymers is preferably 400 to 6,000, in particular 1000 to 4,000. The polydispersity (Q) is generally between 1.5 and 5. Copolymers having epoxy groups of the type mentioned above are distributed, for example, by the company BASF Resins BV under the brand name Joncryl ^® ADR. Joncryl ^® ADR 4468 is particularly suitable. Component v is used in particular in polyester blends containing PLA.

The polyesters and polyester blends according to the invention may preferably contain the following filler materials.

Calcium carbonate can be used, for example, in 10 to 25% by weight, preferably 10 to 20% by weight, particularly preferably 12 to 18% by weight, based on the total weight of the polymer mixture. Among others, calcium carbonate from the Omya company has proven to be suitable. Calcium carbonate generally exhibits an average particle size of 0.5 to 10 micrometers, preferably 1-5, particularly preferably 1-2.5 micrometers.

Talc can be used, for example, in 3 to 40% by weight, preferably 5 to 30% by weight, particularly preferably 15 to 30% by weight, based on the total weight of the polymer mixture. Among others, it has proven to be Talc from Mondo Minerals is suitable. Talc generally exhibits an average particle size of 0.5-10, preferably 1-8, particularly preferably 1-3 micrometers.

Apart from the filler materials calcium carbonate and talc, other minerals may also be present, such as: graphite, gypsum, carbon black, iron oxide, calcium chloride, kaolin, silicon dioxide (quartz), sodium carbonate, titanium dioxide, silicate, wolastonite, mica, montmorillonite, mineral fibers such as glass fibers and natural fibers.

Natural fibers are generally cellulose fibres, Javanese jute fibres, hemp fibres, wood flour or potato peelings. They are preferably used in 1 to 20% by weight, based on the polymer mixture.

Minerals, including calcium carbonate and talc filler materials, can also be used as nanofiller materials. The nanofiller materials are in particular finely divided layered silicates, preferably clay minerals, particularly preferably montmorillonite-containing clay minerals, the surface of which is modified with one or more quaternary ammonium salts and/or phosphonium salts and/or sulfonium salts. Natural montmorillonites and bentonites are preferred as clay minerals.

In short, fillers can be added to polyester mixtures, for example, in the amount of 5 to 35% by weight, based on the total weight of the polymer mixture.

(Co)polyesters with low THF concentration accessible with the process according to the invention, such as PBS, are suitable alone or in polymer mixtures for numerous applications such as injection molded products, thermoformed products, films or foams. . In this regard, (co)polyesters are frequently used in mixtures with other biopolymers, such as polylactic acid, polyhydroxyalkanoates, biologically degradable aliphatic-aromatic polyesters, starches, thermoplasticized starches, mineral filler materials or other additives such as lubricants, filling agents. core formation, plasticizers or pigments.

Preferably, during the manufacture of the polymer blends described in the following documents, the process according to the invention is used: WO 2005/017034, WO 2006/074815, WO 2010/034685, WO 2010/034710, WO 2010/034711 , WO 2010/034712, WO 2011/045293, WO 2011/054786, WO 2011/086030, WO 2012/055796, WO 2012/113744, WO 2012/152820, WO 2013/000847, WO 2013/000892, WO 2013/017431 , WO 2014/075997, WO 2014/075998, WO 2015/169659, WO 2015/169660, WO 2018/114215, PCT/EP2018/058735, PCT/EP2018/071601, PCT/EP2018/0716 07.

Preferred aliphatic and aliphatic-aromatic (co)polyesters and polyester blends containing them are biologically degradable.

In the sense of the present invention, the characteristic "biologically degradable" is then satisfied for a substance or a mixture of substances, when this substance or mixture of substances exhibits, corresponding to DIN EN 13432, a percentage degree of biological degradation of at least 90%.

In general, the biological degradation capacity leads to polyesters/polyester blends decomposing over a measured and verifiable time interval. Degradation can occur by enzymatic, hydrolytic, oxidative and/or by the action of electromagnetic radiation, for example, UV radiation and usually be caused predominantly by the action of microorganisms, such as bacteria, yeasts, fungi and algae. The biological degradation capacity is quantified, for example, by mixing the polyesters with compost and storing them for a certain time. For example, according to DIN EN 13432, CO ^2- free air is allowed to flow through the mature compost during composting and subjected to a defined temperature program. For this, the biological degradation capacity is defined by the relationship of the net release of CO ² by the sample (after deducting the release of CO ² by the compost without sample) to the maximum release of CO ² from the sample (calculated from the carbon content of the sample), as a percentage degree of biological degradation. Biologically degradable polyesters (blends) generally show clear symptoms of degradation, such as fungal growth, formation of cracks and voids, already after a few days of composting.

For example, other methods for determining biological degradation capacity are described in ASTM D 5338 and ASTM D 6400.

EU law 10/2011 establishes limit values for plastic materials that are in contact with food. Unpurified aliphatic polyester packaging materials such as polybutylene succinate (PBS) do not meet the requirements of this standard and are therefore not considered for food applications. In particular, cyclic contaminants in polyesters, such as THF, dimeric monomers, trimers and cyclic tetramers, can migrate from the packaging materials under the different test conditions. The process according to the invention now delivers aliphatic polyesters, whose concentrations of cyclic impurities have clearly decreased and which reach the limit values required by EU law 10/2011. In this regard, the method according to the invention has proven to be more efficient than the procedures described in documents EP-A 228399 and EP-A 2623540.

The method according to the invention is described in more detail below.

The (co)polyesters are manufactured as described in the literature or at the beginning.

At the beginning, the procedure is described for the manufacture in a degassing unit of a (co)polyester where the (co)polyester consists at least partially of 1,4-butylenedicarboxylate units, characterized in that the raw (co)polyester is degassed in the presence of 0.1 to 5% by weight, based on the total weight of the fillers, of an entraining agent, preferably continuously for an average residence time of 0.1 to 2 minutes, and at a pressure between 5 to 300 mbar.

A preferred embodiment relates to a process for the manufacture of a polymer mixture containing one or more (co)polyester(s), which is(are) constituted(s) at least partially by units of 1, 4-butylenedicarboxylate, in a degassing unit that simultaneously acts as a mixing unit, characterized in that the raw (co)polyester is mixed where appropriate with other polymers and auxiliary substances, and is degassed in the presence of 0.1 to 5% in weight, referred to the total weight of the polymer mixture, of an entraining agent such as preferably water, preferably continuously for an average residence time of 0.1 to 2 minutes and at a pressure between 0.1 to 300 mbar - preferably between 5 to 100 mbar.

Mixing and degassing are preferably carried out continuously in an extruder, a continuous kneader (List reactor) or a static mixer. As an example, the following elements are mentioned: in the static mixer, SMR, SMX, SMXL elements or combinations of them can be used, for example, from the company Sulzer Chemtech AG, Switzerland. Examples of a List reactor, depending on the field of application, are: a single-spindle DISCOTHERM B or two-spindle CRP and ORP reactors. Extruders with one or two spindles are considered extruders.

However, mixing and degassing can also be carried out semi-continuously - for example, in a cascade of stirred vessels - or as a batch-continuous process - for example, in a stirred vessel.

Degassing is more efficient by adding an entraining agent. For this purpose, a vacuum is set between 5 and 300 mbar, preferably 5 to 100 mbar and particularly preferably 10 to 60 mbar. The temperatures in the degassing unit are generally 180 to 280 °C and preferably 200 to 250 °C.

In particular, alcohols, such as preferably methanol or ethanol, may also be used as aqueous solutions of alcohol, n-hexane, cyclohexane or acetone as entraining agents. Particularly preferably, water or steam is used as an entraining agent.

The entraining agent is preferably injected into the headspace of the degassing unit. The advantage of this is that it leads to the formation of a homogeneous (co)polyester film in the degassing unit and, for example, the formation of bubbles or foaming in the (co)polyester film is avoided. It may also be advantageous to add to the entraining agent, with mixing, a preferably inert support gas, such as nitrogen, carbon dioxide or air.

The amount of entraining agent is generally between 0.1 and 5% by weight, preferably 0.3 to 2% by weight, based on the crude (co)polyester. Higher amounts of entraining agent can lead to considerable degradation of the (co)polyester in the degassing unit. With a lower concentration of the entraining agent, the decrease in the concentration in the raw polyester of cyclic contaminants such as THF is reduced and is very low.

When using polymer mixtures in the process according to the invention, the amount of entraining agent is generally between 0.1 and 5% by weight, preferably 0.3 to 3% by weight, based on the total weight. of the polymer mixture.

In the batch degassing unit, a reaction time of less than 30 minutes is generally set, and in the continuous process, such as in the extruder, an average residence time of 0.1 to 2 minutes is set. Longer residence times would lead to enhanced degradation of the polycondensed polyester, with shorter residence times the decrease in the concentration of contaminants such as THF is not sufficient. The average residence time can be determined by the volume of melted product in the reactor with respect to the volumetric flow that leaves.

It may also be advantageous to reduce the activity of the reaction catalyst by adding one or more additional amounts of the deactivators described above, such as phosphorous acid.

As degassing units, apart from the preferred twin-screw extruder, also a single-screw extruder, kneader (e.g. Buss kneader), planetary roller extruder are also suitable.

In the process according to the invention the concentration of the contaminants is clearly reduced. As a rule, in polyesters having 1,4-butanediol, the residual THF content of the aliphatic polyester is reduced to half or preferably to a quarter and particularly preferably to a tenth of the original THF content.

As a general rule, the purified aliphatic polyester exhibits a residual THF content of less than 30 ppm, preferably less than 10 and particularly preferably less than 1 ppm.

With the process according to the invention, mixtures of (co)polyester polymers, which have a low concentration of contaminants such as tetrahydrofuran, are practically and efficiently manufactured.

Measurement procedures:

The determination of the viscosity index occurs in accordance with DIN 53728 part 3, January 3, 1985. The mixture of phenol/dichlorobenzene in the weight ratio 50/50 was used as a solvent.

Determination of melt volumetric flow rate (MVR) occurred in accordance with ISO 1133. Test conditions were 190 °C, 2.16 kg. The fusion time was 4 minutes. The MVR indicates the speed of extrusion of a molded part of molten plastic, through an extrusion tool of a given length and diameter, under the conditions described above: temperature, load and piston position. The volume extruded in a given time is determined in the cylinder of an extrusion plastometer.

Application technical measurements:

The molecular weights Mn and Mw of the partially aromatic polyesters were determined according to DIN 55672-1 by CET: elution agent hexafluoroisopropanol (HFIP) 0.05 wt% K salt of trifluoroacetic acid; Calibration occurred with narrow distribution polymethylmethacrylate standards. The evaluation had to be aborted after 18.83 ml (approximately M = 300 g/mol), since for smaller molar masses, the chromatogram was distorted by sample contaminants or the CET elution agent. The melt volumetric rate MVR was measured at 190 °C and 2.16 kg according to ISO 1133-1 DE.

The oligomers were characterized by gas chromatography coupled with mass spectroscopy (GC-MS). 24.41 mg of sample was dissolved in 1.2 ml of dichloromethane. The ampoule was placed for 30 minutes in the roller mixer. Ionization occurred through positive ions, chemical ionization, and collision ionization with electrons. The dissolution occurred by individual dissolution.

Starting substances

Polyester i-1: GS-PLA® FZ91PD, polybutylene succinate from Mitsubishi Chemical Coorp. with an MVR of 4 cm3/10 min

Polyester i-2: BioPBS FZ71PM, polybutylene succinate from Mitsubishi Chemical Coorp. with an MVR of 17 cm3/10 min

Copolyester ii-1: polybutylensebacato-co-terephthalate from the company BASF with an MVR of 1 cm3/10 min Copolyester ii-2: polybutylensebacato-co-terephthalate from the company BASF with an MVR of 9 cm3/10 min Polymer iii-1 : ingeo® 4044D, polylactic acid from NatureWorks with an MVR of 3 cm3/10 min Polymer iii-2: ingeo® 3251D, polylactic acid from NatureWorks with an MVR of 30 cm3/10 min Filler material iv-1: Microtalc IT Extra from the Mondo Minerals company

Lubricant v-1: Erucamide

Entraining agent x: water

Execution of degassing

The tests were carried out in a double spindle extruder with a diameter of 40 mm and a length of 44D. The average residence time of molten product was 15 seconds to 1 minute. The temperatures at the outlet were set to 245 °C. Water was injected into the headspace of the extruder. The other parameters are found in Table 1.

Table 1

Claims (11)

1. Procedure for the manufacture of a (co)polyester, wherein the (co)polyester consists at least partially of 1,4-butylenedicarboxylate units, in a degassing unit, characterized in that the raw (co)polyester is degassed in presence of 0.1 to 5% by weight, referred to the total weight of the starting substances, of an entraining agent at a pressure between 5 to 300 mbar. 2. Procedure for the manufacture of a polymer mixture containing one or more (co)polyester(s), which is at least partially constituted by 1,4-butylenedicarboxylate units, in a degassing unit, which simultaneously acts as mixing unit, characterized in that the raw (co)polyester is mixed, if appropriate, with other polymers and auxiliary substances and is degassed in the presence of 0.1 to 5% by weight, based on the total weight of the polymer mixture, of an entraining agent a pressure between 0.1 to 300 mbar. 3. Method according to claim 1 or 2, characterized in that the entraining agent is water. 4. Method according to claims 1 to 3, characterized in that the entraining agent is injected into the headspace of the degassing unit. 5. Method according to claims 1 to 4, characterized in that the degassing unit is an extruder and is degassed in an average residence time of 0.1 to 2 minutes. 6. Method according to one of claims 1 to 5, characterized in that the degassing unit exhibits an internal temperature of 200 °C to 250 °C. 7. Method according to claim 1, characterized in that it is degassed in the presence of 0.3 to 2% by weight, referred to the total weight of the raw (co)polyester, of the entraining agent water. 8. Method according to claim 2, characterized in that it is degassed in the presence of 0.3 to 3% by weight, referred to the total weight of the polymer mixture, of the entraining agent water. 9. Method according to one of claims 1 to 8, characterized in that the (co)polyester is a polybutylene succinate, polybutylene succinate-coadipate, polybutylene succinate-cosebacate, polybutylene adipate-coterephthalate and/or polybutylene bacatco terephthalate. 10. Method according to claims 1 to 9, characterized in that it is degassed at a pressure between 5 and 100 mbar. 11. Process according to claim 2 or 8, characterized in that the polymer mixture manufactured exhibits a residual THF content of less than 10 ppm, preferably less than 1 ppm.